Cosmos atrosanguineus
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| Cosmos atrosanguineus (Hook.) Voss |
Cosmos atrosanguineus (Chocolate Cosmos) is a species of Cosmos, native to Mexico, where it is extinct in the wild. The species was introduced into cultivation in 1902, where it survives as a single clone reproduced by vegetative propagation.
It is a herbaceous perennial plant growing to 40-60 cm tall, with a fleshy tuberous root. The leaves are 7-15 cm long, pinnate, with leaflets 2-5 cm long. The flowers are produced in a capitulum 3-4.5 cm diameter, dark red to maroon-dark brown, with a ring of six to ten (usually eight) broad ray florets and a center of disc florets; they have a light vanillin fragrance (like many chocolates), which becomes more noticeable as the summer day wears on.
[edit] Cultivation and uses
The single surviving clone is a popular ornamental plant, grown for its rich dark red-brown flowers. It is not self-fertile, so no viable seeds are produced, and the plant has to be propagated by division of the tubers.
It requires partial sun or full sun, and flowers from mid to late summer. It is frost-sensitive; in temperate zones, the tuber has to be dug up and stored in a frost-free store over the winter.
[edit] References
- Huxley, A. (ed.) 1992. New RHS Dictionary of Gardening 1: 739. Macmillan.
Cosmos atrosanguineus This is an attractive, popular, chocolate-scented garden plant, but is believed to be extinct in the wild. It was first discovered in Mexico in the 1860s, and has remained in cultivation ever since, gaining an RHS Award of Merit for Exhibition in 1938. It has not, however, been re-discovered in the wild, although plants are now being re-introduced from micropropagated material at the Royal Botanic Gardens, Kew. Until recently, all the plants in cultivation were thought to be a single clone that was self-incompatible and therefore did not set seed. A fertile form called ‘Pinot Noir’ has now been introduced to cultivation from New Zealand and is protected in most countries by Plant Breeders’ Rights. Cosmos atrosanguineus is widely available, but the cultivar ‘Pinot Noir’ has not yet made it into the RHS Plant Finder – maybe next year?
Reference RHS Plantfinder 2006, Plant Conservation p 12
edited Janet Cubey
February 2006
